Translation
For the living know that they will die, but the dead know nothing; they have no more reward, their memory is forgotten.
Paraphrase
The living know that they will die, but they keep pressing on until that time comes; in contrast the dead know nothing at all; they have no further reward beyond what they have already received, and even the reward that you would expect to linger after them, i.e. the memory of them, is also lost.